Folding of sheets of material (e.g., paper, napkins, paper towels, tissue, etc.) is frequently performed using a pair of folding rolls that have interacting mechanical gripper and tucker assemblies. The gripper and tucker assemblies are uniformly spaced around a circumference of each respective folding roll to interact with one another so as to interfold the sheets of material. The tucker assemblies on one roll interact with the gripper assemblies of the adjacent roll, and vice versa, to alternately grip and tuck successive sheets of material fed between the rolls. As the rolls rotate, the gripper assemblies carry and release the folded sheets of material to create a zigzagged interfolded stack of sheets.
Typically, each tucker assembly includes a rigid structure, referred to as a tucker, that protrudes from a slot or cavity in the outer surface of its the folding roll, and each gripper assembly is contained within a recess or slot in the folding roll. The tucker terminates in a point that extends outwardly of the outer surface of the folding roll, and is rigidly fixed in the slot or cavity in the folding roll to interface with a gripper assembly on the adjacent folding roll. As both the first and second folding rolls rotate, the tuckers that protrude from the outer surface of the first folding roll engage the gripper assemblies of the adjacent second folding roll, and vice versa. The sheets are fed between the first and second folding rolls, such that engagement of the tuckers and grippers of the folding rolls functions to fold the sheets during advancement of the sheets between the folding rolls. However, the protruding tucker typically rotates at a surface speed greater than the recessed gripper assembly in the adjacent roll, which can cause a snapped release of the tucker that interrupts and bounces the gripper assembly. The bounce can cause the gripper assembly to release the sheet of material and interrupt the output of the interfolding machine. Also, in the event the timing between the grippers and tuckers becomes disrupted, the interfolding machine can jam and the tucker can cause damage to the gripper and to the surface of the folding roll.
There is thus a need for a tucker assembly for a folding roll of an interfolder that can accommodate the difference in surface speed between the points of the tuckers and the grippers. There is also a need for a tucker that is capable of accommodating variations in the location of engagement of the tucker with the gripper, to prevent jamming that can occur when the timing between the rolls is disrupted.